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<div class="titlepage"><div><div><h3 class="title">
<a name="boost_asio.reference.buffer_copy"></a><a class="link" href="buffer_copy.html" title="buffer_copy">buffer_copy</a>
</h3></div></div></div>
<p>
        <a class="indexterm" name="boost_asio.indexterm.buffer_copy"></a>
      </p>
<p>
        The <a class="link" href="buffer_copy.html" title="buffer_copy"><code class="computeroutput"><span class="identifier">buffer_copy</span></code></a>
        function is used to copy bytes from a source buffer (or buffer sequence)
        to a target buffer (or buffer sequence).
      </p>
<p>
        Copies bytes from a source buffer sequence to a target buffer sequence.
      </p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">MutableBufferSequence</a><span class="special">,</span>
    <span class="keyword">typename</span> <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a><span class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <a class="link" href="buffer_copy/overload1.html" title="buffer_copy (1 of 2 overloads)">buffer_copy</a><span class="special">(</span>
    <span class="keyword">const</span> <span class="identifier">MutableBufferSequence</span> <span class="special">&amp;</span> <span class="identifier">target</span><span class="special">,</span>
    <span class="keyword">const</span> <span class="identifier">ConstBufferSequence</span> <span class="special">&amp;</span> <span class="identifier">source</span><span class="special">);</span>
  <span class="emphasis"><em>» <a class="link" href="buffer_copy/overload1.html" title="buffer_copy (1 of 2 overloads)">more...</a></em></span>
</pre>
<p>
        Copies a limited number of bytes from a source buffer sequence to a target
        buffer sequence.
      </p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">MutableBufferSequence</a><span class="special">,</span>
    <span class="keyword">typename</span> <a class="link" href="ConstBufferSequence.html" title="Constant buffer sequence requirements">ConstBufferSequence</a><span class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <a class="link" href="buffer_copy/overload2.html" title="buffer_copy (2 of 2 overloads)">buffer_copy</a><span class="special">(</span>
    <span class="keyword">const</span> <span class="identifier">MutableBufferSequence</span> <span class="special">&amp;</span> <span class="identifier">target</span><span class="special">,</span>
    <span class="keyword">const</span> <span class="identifier">ConstBufferSequence</span> <span class="special">&amp;</span> <span class="identifier">source</span><span class="special">,</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_bytes_to_copy</span><span class="special">);</span>
  <span class="emphasis"><em>» <a class="link" href="buffer_copy/overload2.html" title="buffer_copy (2 of 2 overloads)">more...</a></em></span>
</pre>
<p>
        The <code class="computeroutput"><span class="identifier">buffer_copy</span></code> function
        is available in two forms:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
            A 2-argument form: <code class="computeroutput"><span class="identifier">buffer_copy</span><span class="special">(</span><span class="identifier">target</span><span class="special">,</span> <span class="identifier">source</span><span class="special">)</span></code>
          </li>
<li class="listitem">
            A 3-argument form: <code class="computeroutput"><span class="identifier">buffer_copy</span><span class="special">(</span><span class="identifier">target</span><span class="special">,</span> <span class="identifier">source</span><span class="special">,</span> <span class="identifier">max_bytes_to_copy</span><span class="special">)</span></code>
          </li>
</ul></div>
<p>
        Both forms return the number of bytes actually copied. The number of bytes
        copied is the lesser of:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
            <code class="computeroutput"><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">target</span><span class="special">)</span></code>
          </li>
<li class="listitem">
            <code class="computeroutput"><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">source</span><span class="special">)</span></code>
          </li>
<li class="listitem">
            <code class="computeroutput"><span class="identifier">If</span></code> specified, <code class="computeroutput"><span class="identifier">max_bytes_to_copy</span></code>.
          </li>
</ul></div>
<p>
        This prevents buffer overflow, regardless of the buffer sizes used in the
        copy operation.
      </p>
<p>
        Note that <a class="link" href="buffer_copy.html" title="buffer_copy"><code class="computeroutput"><span class="identifier">buffer_copy</span></code></a> is implemented in terms
        of <code class="computeroutput"><span class="identifier">memcpy</span></code>, and consequently
        it cannot be used to copy between overlapping memory regions.
      </p>
<h5>
<a name="boost_asio.reference.buffer_copy.h0"></a>
        <span class="phrase"><a name="boost_asio.reference.buffer_copy.requirements"></a></span><a class="link" href="buffer_copy.html#boost_asio.reference.buffer_copy.requirements">Requirements</a>
      </h5>
<p>
        <span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/buffer.hpp</code>
      </p>
<p>
        <span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code>
      </p>
</div>
<div class="copyright-footer">Copyright © 2003-2025 Christopher M.
      Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
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